Abstract. Progress in observational cosmology over the past five
years has
established that the Universe is dominated dynamically by dark matter
and dark energy. Both these new and apparently independent forms of
matter-energy have properties that are inconsistent with anything in
the existing standard model of particle physics, and it appears that
the latter must be extended. We review what is known about dark matter
and energy from their impact on the light of the night sky.
Most of the candidates that have been proposed so far are not perfectly
black, but decay into or otherwise interact with photons in characteristic
ways that can be accurately modelled and compared with observational data.
We show how experimental limits on the intensity of cosmic background
radiation in the microwave, infrared, optical, ultraviolet, x-ray and
-ray bands
put strong limits on decaying vacuum energy,
light axions, neutrinos, unstable weakly-interacting massive particles
(WIMPs) and objects like black holes. Our conclusion is that the
dark matter is most likely to be WIMPs if conventional cosmology holds;
or higher-dimensional sources if spacetime needs to be extended.